The invention relates to a sorting device for sorting a mixture of materials, also referred to in the following as a material mixture, into fractions of different grain. The sorting device can then in particular be disposed to sort the material mixture according to grain size or another geometric grain characteristic or according to grain weight or another physical characteristic. The sorting device can also be disposed to sort according to different geometric or physical characteristics, for example grain size and a physical characteristic such as for example grain weight and/or an electrical and/or magnetic characteristic. Preferably, the sorting device is disposed to sort according to grain size. Preferred applications include separating different fractions from material mixtures such as for example excavated earth, quarry waste, earth-stone mixtures in general, organic waste, bulky waste of any kind, electrical waste, scrap metal from recycling cars, household and commercial refuse, waste wood and so on.
In order to sort and separate material fractions from material mixtures of the kind mentioned, correspondingly large-volume, stable sorting devices are required. Sorting by means of a roller screen, which comprises a number of rotary-driven rollers arranged alongside each other, has proven effective. The material mixture which is conveyed onto the roller screen is sorted and/or separated by the roller screen into at least two grain fractions, namely one fraction of coarser grain—the oversize grain—which is conveyed on the roller screen to a side edge of the roller screen, and a comparatively finer undersize grain and/or fine grain which falls through the roller screen. The fractions which are separated from each other in this way, i.e. the fine grain and the oversize grain, are discharged and transported away or are additionally sorted in one or more downstream sorting stages of the sorting device.
Roller screens consisting of disc rollers, star rollers or in particular spiral rollers, which may also be referred to as helical rollers, are known. Roller screens of this kind which have proven effective in practice are disclosed in EP 1 570 919 B1 and EP 1 088 599 B1.
Sorting devices for material mixtures of the kind mentioned are typically stationary systems, not least because of their size, which are operated at the same site for years and embodied in accordance with the local available space. If, however, the material flows to be treated are encountered only once or periodically or at different times at different sites of the same operator, or if there is only limited on-site space available for setting up the sorting device, then a desire arises for a compact design or for mobility or even for renting the sorting device just for periods of time.
It is therefore an object of the invention to provide a sorting device of the kind described which enables a material mixture to be sorted into at least two different material fractions at a high material throughput and which is embodied in a compact design. The sorting device should be sufficiently compact in its design that it can be transported as a whole, in one unit, by road or rail, wherein this includes embodiments as a sorting device which can be driven by itself or towed or transported on a platform.